changed to railway=level_crossing

because sql query only returns railway=level_crossing, so my guess is this was a typo
Merge pull request #98 from JPaulW/level_crossings

changed to railway=level_crossing
Add round line-joins to (the black) bridge casings.

Fixes #74
Merge branch 'master' of https://github.com/gravitystorm/openstreetmap-carto into disused_stations